Venezuela's opposition is demanding that the government explain how a former Iranian official ended up with a cheque in Venezuelan currency worth about $70 million (NZ$83 million).

Venezuela's opposition coalition said in a statement on Monday (local time) that the government should clear up why the Iranian had a cheque for 300 million Venezuelan bolivars that was found by German customs authorities.

The German newspaper Bild am Sonntag reported in its Sunday edition that the man who was trying to enter Germany with the cheque was Tahmasb Mazaheri, Iran's former central bank chief.

The weekly reported that customs officials at Duesseldorf airport found the cheque in his luggage on January 21 upon his arrival from Turkey, and that Mazaheri told authorities the money was to be used for the construction of 10,000 apartments funded by the Venezuelan government.

President Hugo Chavez's government has built close ties with Iran's government in recent years, and Iran has helped build public housing in the country.

Opposition official Ramon Jose Medina called it a "clear irregularity" and said there should be a thorough investigation.

"We demand that there be an immediate explanation to the country about those funds," Medina said in the opposition coalition's statement.

Opposition leader Henrique Capriles also expressed concern, saying in a message on Twitter on Sunday: "What explanation will the government give Venezuelans about what happened with the Iranian ex-minister?"

Venezuelan government officials have yet to comment on the matter. Officials at Iran's embassies in Caracas and Berlin could not be reached for comment.

German customs had issued a statement on Friday saying that a cheque for 300 million Venezuelan bolivars issued by the Bank of Venezuela was found on an unidentified 59-year-old man. They have declined to identify the man, who is now free to go about his business while officials investigate the funds.